As is well known, when a person showers or bathes with hot water in a bathroom steam is naturally produced, which results in glass surfaces becoming fogged and specifically the surface of a mirror located in such bathroom.
A number of invention Patents and Utility Models are known related to devices for de-fogging bathroom mirrors, which mainly comprise electrical resistors which, duly placed in contact with the rear or silvered surface of the mirror, heat it and thus de-fog the mirrored surface.
Such devices which rely on heating by means of electrical resistors present two fundamental disadvantages: on one hand a high electrical power consumption; and on the other, problems inherent to the installation, as there are safety regulations concerning electrical devices in bathrooms which must be observed, so that providing means of operation involving electrical resistors for heating mirrors or of any other nature in a bathroom involves a certain risk and danger, unless the installation is perfectly carried out with all required safety measures.
Utility Model n.degree. 282.980 describes an improved device for preventing fogging of bathroom mirrors, here employing hot water from the heating radiators, consisting of placing next to the rear face of the mirror a layer of electrically insulating material inside which is included an insulated heat source consisting of low-power electrical resistors, with the property that said Utility Model also claims that the heat source may consist of a coil derived from the heating radiator.
When the device of this Utility Model employs electrical resistors as a heat source to prevent fogging of the mirror it will present the aforementioned disadvantages, that is, a high electrical power consumption and the risk inherent to any electrical devices operating in a bathroom.
However, when the heat source consists of a coil by-passed from the heating radiator, the energy consumption is minimal and, more relevantly, the risk is inexistent, although a basic problem exists, which is that the device will only work when the heating is on, to which must be added that heat transmission between the coil and the mirror is exclusively by radiation, which implies both great heat losses to the air between the coil tubes and de-fogging only in the areas of contact between the coil and the mirror, with a long time required to de-fog the entire surface of the mirror.